Many traffic surveillance systems have been developed to monitor vehicle traffic in real time. The monitoring techniques used by developed nations may include global positioning system (“GPS”) devices fixed to vehicles, fixed-position cameras, inductive loop vehicle detectors in the roads, Doppler radar, and so on. Based on the collected information, these systems typically estimate the speed and volume of the traffic at various locations. Because the roads are typically in good condition and traffic typically proceeds in an orderly manner in developed nations, the speed and volume information can be quite useful indications of traffic patterns. The speed and volume information can be reported to drivers (e.g., via a web site and a dedicated traffic reporting device) so that they can plan their trips accordingly. Some drivers may move up or delay their anticipated departure times or select alternative routes based on the reported information. The speed and volume information can also be reported to a department of transportation to help control the rate at which vehicles enter the flow of traffic. Because the costs of these techniques for monitoring traffic are quite high, traffic is typically monitored only at the busiest stretches of roads.
These monitoring techniques, however, may not provide predictions of traffic patterns that are as useful in developing nations for various reasons. One reason is that the road quality tends to be quite variable in developing nations. For example, bumpy roads and potholes may be common even in city centers. Another reason is that many different types of vehicles may be used in developing nations. For example, roads may be congested by two-wheeled vehicles (e.g., scooters), three-wheeled vehicles (e.g., automatic rickshaws), four-wheeled vehicles (e.g., passenger cars), and larger-number-wheeled vehicles (e.g., buses and trucks). Each type of vehicle may only be able to travel at certain speeds depending on the road conditions. For example, only two-wheeled vehicles may be able to travel on certain narrow or bumpy roads. Another reason is that traffic flows may be more chaotic because drivers in developing nations may not adhere to right-of-way protocols at intersections and may rely on sounding their horns to help establish their right-of-way. Although such sounding of horns is socially unacceptable or illegal in many developed nations, it is acceptable and quite common in many developing nations.